Changes in the methods of investigation have had a crucial impact on progress in mineralogy. Many important methods have emerged with their own parameters, interpretations, problems, new albeit restricted possibilities and scopes, and with their own instrumentation and measurement tools. Even the aims and contents of the investigations have changed. Two processes can be discerned:
1. The logical completion of developing and elaborating the methods, i.e. determining all physical principles based on a single, general, multifaceted phenomenon: the interaction of radiation (particles) with matter.
These interactions and hence these methods can be presented schematically by two coordinates. One is energy (or wavelength of radiation) and parts of the electromagnetic spectrum (nuclear, X-ray and electron, UV, visible, IR, microwave, SHF and RF). The other coordinate is represented by the modes of interaction (spectroscopy-absorption, emission, scattering-diffractometry, microscopy). The various intersection points in this system of coordinates have already been determined and elaborated in detail according to theoretical and instrumentational aspects.